Waterbed vibrator

ABSTRACT

A vibrator mechanism, including a transducer and driving circuit, particularly adapted to vibrating a waterbed, includes two independently controlled vibration sources, each of which can generate vibration of varying amplitude and frequency. These two sources are typically mounted at opposite ends of a waterbed frame and vibrated at different frequencies so that interference waves may be produced within the water of the bed to produce a pleasing effect for the user. Additional circuitry is described which provides a time varying frequency and amplitude for each of the vibrators, and this circuitry is in turn controlled by a clock circuit so that, by using the time varying frequency and amplitude, the user may be slowly lulled to sleep or slowly awakened using the vibration within the waterbed as a stimulus for controlling the rate of falling asleep and waking up.

This is a division of application Ser. No. 800,588, filed May 25, 1977,now abandoned.

BACKGROUND OF THE INVENTION

The vibration of articles of furniture for inducing relaxation in theuser has been accomplished in the prior art using a variety ofmechanisms. Because of the ready availability of high power, 60-cyclecurrent, however, the bulk of these systems have used either a direct60-cycle transducer to induce vibration or a motor with an eccentricweight operating from the 60-cycle current. In some instances where amotor with an eccentric weight is used, the speed of the motor isvariable, for example, using a solid state control or a rheostat. Suchdevices, however, necessarily control the amplitude and frequency ofvibration simultaneously, and it is impossible, without altering theeccentricity of the weight (a difficult operation) to alter thefrequency and vibration independently.

In systems where two eccentric weight motors are used on a single pieceof furniture, it has been found that interference waves can be producedin the furniture, which waves result in a pleasant sensation for theuser. These systems, however, as mentioned above, can produce suchinterference waves only at predetermined amplitudes depending completelyupon the frequency selected for motor operation.

Thus, in the prior art, vibration transducers have typically beenlimited to operation from the available 60-cycle current and have notbeen utilized to independently vary the frequency and amplitude of thevibration. Motors used in the prior art are limited in the variation ofwaves which may be induced and, furthermore, are subject to substantialwear generated by the eccentric weight.

SUMMARY OF THE INVENTION

The present invention alleviates these and other difficulties inherentin prior art furniture vibrator designs by utilizing a solid statedriving circuit in conjunction with a vibration transducer to generatevibration in furniture, and particularly in waterbeds, havingindependently variable amplitude and frequency characteristics. In aparticular embodiment of the present invention, two such vibrationsystems are used so that interference waves may be produced within thefurniture of varying amplitude and frequency.

The present invention further provides the ability to induce in thevibration system a time varying amplitude and frequency characteristicwhich is particularly adaptable for use in combination with an alarmclock circuit for slowly inducing sleep or slowly waking up the user.When this circuit is used in combination with a pair of transducers andvibrators, it is possible to slowly induce sleep or wake the operator upwhile at the same time producing pleasant interference waves within thefurniture by vibrating the pair of transducers at different frequencies.

The ability to independently vary the amplitude and frequency of avibrator attached to furniture, and particularly to waterbeds, isextremely important in that substantially different effects can beachieved by producing, for example, low frequency, high amplitude wavesas opposed to high frequency, low amplitude wave motion within the bed,one of which may induce a very relaxed state in the user whereas theother may heighten the awareness and sensitivity of the user.

These and other features of the present invention are best understoodthrough the following detailed description which references the drawingsin which:

FIG. 1 is a perspective view showing the vibration mechanism of thepresent invention attached to the underside of a typical waterbed;

FIG. 2 is an elevation view of the vibration transducer utilized in thesystem shown in FIG. 1;

FIG. 3 is a block diagram illustration of the circuitry used for drivingthe transducers of FIG. 2;

FIG. 4 is a schematic illustration of signal levels on various lines ofthe circuit of FIG. 3, illustrating frequency adjustments;

FIG. 5 is a schematic illustration similar to that of FIG. 4, butillustrating amplitude adjustments;

FIG. 6 is a schematic illustration of signals on other lines of thecircuit of FIG. 3, illustrating the alarm operation of the circuit;

FIG. 7 is a schematic illustration similar to that of FIG. 6, butillustrating the sleep inducing operation of the circuit; and

FIG. 8 is a detailed circuit diagram showing the circuits which make upthe black box members of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIG. 1, a typical waterbed is shown to include adeck support grid 11, formed of vertical support members, positionedbelow and supporting a flat, horizontal deck member 13. These elements11,13 are typically constructed of wood and are used to support aflexible water mattress 15 above the floor. Attached to the underside ofthe deck 13, preferably at diagonally opposed corners of the deck 13,are a pair of vibration transducers 17,19. Each of the transducers 17,19is connected electrically to a driving circuit 21 by means of wires 23and 25, respectively.

The system of the present invention permits each of the transducers 17and 19 to be independently energized at varying amplitudes andfrequencies. When the transducers 17 and 19 are operated at differentfrequencies, each of these frequencies will be induced in the water ofthe mattress 15 and will be felt by anyone lying on the mattress 15. Inaddition, an interference frequency, the difference between thefrequencies of the transducers 17 and 19, will form an interference wavewithin the mattress 15 which can also be felt by the user. Thisinterference wave can typically be of extremely low frequency while, atthe same time, each of the transducers is producing a primary, higherfrequency. For example, if the transducer 17 is vibrating at 45 cyclesper second and the transducer 19 at 42 cycles per second, they willproduce an interference wave of 3 cycles per second. This low frequencyinterference wave can be extremely soothing to the user and can producean altogether different sensation from that produced by the directvibration of either of the transducers 17,19 alone.

Referring now to FIG. 2, the particular transducer utilized in thesystem of FIG. 1 will be described. As previously stated, the transducer17 is connected to the deck 13. In the preferred embodiment, it includesa generally u-shaped band of spring steel 27, one flat side of which isconnected, as by plural screws 29, to the deck 13. The band 27 ispreferably isolated from the deck 15 by washers 31. The opposite flatside of the u-shaped band 27 mounts a magnet coil 33. This coil, whenenergized, will attract the opposite flat side of the u-shaped springsteel band 27. Thus, when the magnet coil 33 is induced with a cyclicalcurrent, it will vibrate, so that the free side of the u-shaped springsteel band 27 is forced to oscillate relative the stationary side. Sincethe magnet 33 is relatively heavy, this vibration will, in turn, inducevibration in the deck 13 and in the mattress 15 above the deck. Thetransducer 17 is capable of vibrating at a variety of frequencies,depending upon the inducing current, and the amplitude of vibration canbe varied by altering the level of the inducing current, as will bedescribed in detail below.

Referring now to FIG. 3, the transducers 17 and 19 are shown togetherwith the control circuit which forms the driving circuit 21 of FIG. 1.This circuit includes a pair of astable multivibrators 35 and 37 areshown connected to a control line 39 which, together with a pair ofvariable resistors 41 and 43, controls the multivibrator frequency. Itwill be understood that each of the astable multivibrators 35,37produces an output square wave, the frequency of which is determined bythe setting of the variable resistors 41,43 or the voltage on thecontrol line 39.

The output of each of the astable multivibrators 35,37 is conducted bymeans of a pulse shaping circuit 45,47, respectively, to a pair ofmonostable multivibrators 49,51. The monostable multivibrators areresponsive to the output frequency signal from astable multivibrators35,37 to produce a controlled duration output pulse for each negativegoing input pulse from the pulse shape circuits 45,47 so that, on theiroutput lines 53,55, respectively, the multivibrators 49,51 each producea signal, the frequency of which is determined by the astablemultivibrators 35,37 and the pulse width of which is determined by themonostable multivibrators 49,51. This pulse width ultimately determinesthe amplitude of vibration produced by the system. In a manner similarto the resistors 41,43, variable resistors 52,54 control the time delayof the monostable multivibrators 49 and 51, respectively. Additionally,this time delay may be set by a control signal on line 60.

Referring briefly to FIG. 4, the output of astable multivibrator 35 isshown as a function of time and, for purposes of illustration, is shownas having a first relatively low frequency during a time period T₁ and asecond relatively high frequency during a time period T₂. Correspondingwith this output, the output of the pulse shape circuit 45 is shown, asis the output of monostable multivibrator 49.

In this example, the pulse width of the monostable multivibrator 49 isleft unchanged as the frequency of the astable multivibrator 35 changes.It can be seen that the frequency at the output of the monostablemultivibrator 49 changes significantly between times T₁ and T₂, but thepulse width does not appreciably change.

In the illustration of FIG. 5, times T₃ and T₄ are shown and the outputsof elements 35, 45, and 49 are again depicted. In this example, however,the setting of the astable multivibrator 35 is left unchanged, so thatthe frequency remains constant. During the time T₃, the monostablemultivibrator 49 is set for a relatively short time delay, so that theamplitude of vibration will be relatively small. During the time T₄,however, the monostable multivibrator 49 has an increased time delay, sothat the output pulse width, and the resulting amplitude of vibration,is substantially increased without altering the output frequency.

From the diagrams of FIGS. 4 and 5 it can be seen that any combinationof output frequency and amplitude which is desired may be achieved byindependently varying the resistors 41 and 43 for frequency adjustment,and the resistors 52 and 54 for amplitude of vibration adjustment.

Referring once again to FIG. 3, the output signals on lines 53 and 55are coupled to driver amplifiers 61 and 63, respectively, which are inturn connected to drive the transducers 17,19 in accordance with thesignals on lines 53,55.

While the frequency and amplitude of vibration may be controlled aspreviously described using the variable resistors 41, 43, 52, and 54,the present invention includes an alternate control responsive to adigital clock circuit 65. This clock circuit produces an alarm signal online 67 in typical fashion, which is used to drive a mode controlcircuit 68 at the time for which the alarm of the digital clock 65 isset. Once it is set, the mode control 68 drives an integrator 71 whichproduces a negative-going ramp signal on line 73. An inverted,positive-going ramp signal is produced on line 75 by an invertingamplifier 77 in response to the signal on line 73.

The mode control 68 includes, as a second input, a sleep switch 81 whichis closed by the operator to place the circuit 21 in a sleep inducingmode. Either of the inputs, 81,67, will initiate control signals fromthe mode control 68 to enable the integrator 71. In addition, however,the mode control operates a double pole, double throw switch 83 inaccordance with the initiating signal 67,81. Thus, the mode control 68controls the switch 83 to connect line 39 to line 73 and line 60 to line75 during the alarm period (line 67 signal) or, alternatively, line 60to line 73 and line 39 to line 75 during the sleep inducing period(switch 81).

In addition, the mode control 68 automatically produces a signal on aline 184 which enables the multivibrators 35,37,49,51 during the alarmand sleep inducing modes. A switch 183 is also provided for manuallyenabling the multivibrators 35,37,49,51.

The output of the inverting amplifier 77 and mode control 68 areadditionally connected to an alarm and reset control 86 which monitorsthe output voltage on line 75 and provides an output signal on a line 87when the alarm ramp signal has terminated. This signal on line 87 drivesa speaker 96 to give an audible alarm sound indicating that the alarmcycle is completed. The speaker 96 assures that the operator wakes up.

Referring to FIGS. 6 and 7, the integrator 71 ramp signal, inverter 77ramp signal, and the control of the multivibrators 35, 37, 49, and 51 inresponse to these signals will be described. FIG. 6 shows the alarmsequence, that is, the sequence normally utilized in the morning toslowly wake the operator prior to the energization of the audio speaker96. It will be seen that, during a predetermined time period, the outputof the integrator 71 is a linearly decreasing ramp signal while theoutput of the inverting amplifier 77 is a linearly increasing rampsignal. The rates of change of these signals in FIGS. 6 and 7 aregreatly exaggerated to ease understanding, the transitions actuallyoccurring over an extended period of time, for example, 1/2 hour.

The multivibrators 35 and 37 respond to the ramp signal from theintegrator 71 by producing an output frequency which increases linearlywith time. The multivibrators 49 and 51 simultaneously respond to theoutput from the inverting amplifier 77 by producing a linearlyincreasing amplitude signal. Thus, during this alarm period, both thefrequency and the amplitude of vibration are linearly increased untilthey reach the levels preset by resistors 41, 43, 52, and 54. Thisincreasing frequency and amplitude slowly brings the user from asubconscious sleep level to a level of heightened awareness, at the endof which the alarm 96 sounds, finally waking the operator.

As shown in FIG. 7, when the sleep switch 81 is closed, the output ofthe integrator 71 and the inverting amplifiers 77 are identical to thatshown in FIG. 6. In this case, however, the interconnections arereversed by the double pole, double throw switch 83, so that theintegrator 71 controls the multivibrators 49 and 51 and the invertingamplifier 77 controls the multivibrators 35 and 37. The result of thisswitching is that the frequency as well as the amplitude of the outputsignal from the monostable multivibrators 49,51 are reduced from thevalue preset by resistors 41, 43, 52, and 54 to a very low frequency,low amplitude level, slowly bringing the operator from a level ofheightened awareness to a level of relatively deep sleep.

It will be seen that by altering the values of resistors 41 and 43,interference waves can be generated during the sleep and alarm phases ofoperation as may be desired. The present circuit thus permits a veryunique system for producing time variations in the frequency andamplitude of vibration to lull the user to sleep or to slowly waken himas desired.

Referring now to FIG. 8, the detailed circuitry, represented in blockform in FIG. 3, will be described.

A power supply 101 supplies a V+ voltage on output line 103 which isreferenced to an output neutral or ground line 105. This voltage isproduced by a stepping transformer 107, the secondary of which isconnected in series with a filtering capacitor 111 and rectifying diode180, which is used, together with resistor 115 and reference diode 113for controlling a regulating transistor 117 to provide the desiredvoltage. In addition, the power supply 101 provides filtered drivingcurrent for the vibrators 17,19 by connecting a capacitor 121 andrectifying diode 178 in series with the 60-cycle source. A pair ofoutput lines 105,119 are connected in shunt with the filter capacitor121 and a bleeder resistor 123.

The astable multivibrators 35 and 37 are identical in construction andthus only the multivibrator 35 will be described. This multivibratoruses an integrated circuit 124 commonly available in the art understandardized part number NE555 (or others). Pin 8 of this integratedcircuit is connected to line 103 and pin 1 thereof is connected to line105 for powering the integrated circuit. Fixed resistors 125 and 127,along with variable resistor 41 and capacitor 131, all connected inseries between lines 103 and 105, are connected at their junctions topins 2, 6, and 7 of the integrated circuit 124. These components 125,127, 41, and 131 control the frequency of the astable multivibratorconfigured integrated circuit 124 in the absence of a voltage controlsignal on pin 5.

Pin 4 of the integrated circuit 124 is connected to line 184 forenabling (when a signal is present on line 184) or disabling (when nosignal is present) the integrated circuit 124.

Line 39, previously mentioned, is connected to pin 5 of the astablemultivibrator 124 and will alter the bias on pins 2, 6, and 7 to set thefree running frequency of the multivibrator 124 when a voltage ispresent. As the voltage on line 39 increases, the frequency of theintegrated circuit 124 will decrease.

As previously mentioned, the output at pin 3, line 135, is a squarewave, the frequency of which is controlled by the variable resistor 41or the voltage on line 35, is the latter is above ground level, that is,the level on line 105.

Each of the output lines 135 of the multivibrators 35 and 37 areconnected to a balance indicator light 137, comprising a resistor 139,diode 141, and light emitting diode 143 connected in series betweenthese outputs. The light emitting diode 143 is mounted on the frontpanel of the circuit chassis and is illuminated to show maximumintensity in a cyclicly changing pattern, the frequency of which isequal to the difference frequency between the astable multivibrators 35and 37. As previously mentioned, this difference in frequency is theinterference wave frequency within the waterbed and the light emittingdiode 143 makes it easy for the user to adjust the frequencies of themultivibrators 35 and 37 to provide a desired difference frequency.

The outputs of each of the astable multivibrators on lines 135 areadditionally connected to the inputs of the monostable multivibrators 49and 51. These multivibrators are also identical in construction, thusonly multivibrator 49 will be described. This multivibrator is alsobuilt around an NE555 integrated circuit 147, including pin 8, connectedto line 103 and pin 1 connected to line 105 for supplying power to thecircuit. The output on line 135 from the astable multivibrator 35 isconnected to the input at pin 2 of the integrated circuit 147 through apulse shaping capacitor 45. The capacitor 45 produces negative goingpulses at the trailing edge of the output square wave on line 135 fortriggering the multivibrator 49. The input on pin 2 of the integratedcircuit 147 is responsive only to the negative going pulses, such thatthe frequency of the integrated circuit 147, but not its pulse duration,is identical to the frequency of the signal on line 135.

Pins 6 and 7 of the integrated circuit 147 are each connected at thejunction of the variable resistor 52 and capacitor 151 which are, inturn, connected in series with a fixed resistor 153 between the V+ line103 and ground 105. The variable resistor 52 sets the pulse duration ofthe monostable multivibrator 49 and thus the intensity of vibrationcaused by the waterbed vibrator. It can be seen, therefore, that theresistor 52, in setting the pulse duration, changes the vibrationamplitude independent of the frequency, which is determined by theresistor 41 or the signal on line 39.

A voltage control signal on line 60 is connected to pin 5 of theintegrated circuit 147 and alters the pulse duration signal at pin 6, ifit is enabled. As the voltage on line 60 increases, the pulse width ofthe monostable multivibrator 49 increases, that is, the time periodduring which the output voltage is high is increased. The output at pin3, line 153, is thus a rectangular wave, the frequency of which isdetermined by the astable multivibrator integrated circuit 124 and thepulse duration of which is determined by the monostable multivibratorintegrated circuit 147. As with the astable multivibrator, a signalsupplied to pin 4 from line 184 enables or disables the monostablemultivibrator 49.

The outputs of the monostable multivibrators 49 and 51 are connectedthrough bias resistors 155 to driver amplifiers 61 and 63. Theseamplifiers are identical in construction and only the amplifier 61 willbe described. The amplifier 61 includes a transistor 157 which isoperated as a switch, that is, either totally cut off or saturated. Whenthe output on line 153 is at ground level, the transistor 157 is cutoff. When the output on line 153 is high, the transistor 157 issaturated and thus conductive. When conductive, the voltage on lines 119and 105 appears across the vibrator or transducer 17 and the currentthrough the vibrator 17 increases until limited by the resistance of thevibrator. When the transistor 157 cuts off, the inductance of thevibrator 17 is prohibited from damaging the transistor 157 by a shuntingdiode 159 in typical fashion. The vibrator 19 is operated in anidentical fashion from the driver amplifier 63.

Turning now to the control circuitry used for operating this vibratorcircuit, a digital clock 65, in the form of an integrated circuit chip,readily available on the market, is supplied with operating voltagesfrom lines 103 and 105 and provides, at a time set by the operator, analarm signal on line 67. An alarm reset input on line 163 responds tonegative going pulse signals to reset the alarm circuit of the clock 65.The line 163 is normally clamped through a resistor 165 to the voltageon line 103.

Signals on the line 67, indicating that the alarm time has been reached,set a pair of flip-flops 69 and 79 which form a part of the mode control68. A diode 167 prevents the signal from attempting to both set andreset the flip-flop 79 at the same time. The flip-flop 69 is used tocycle the vibrators, whereas the flip-flop 79 determines the directionof cycling, that is, whether the vibrator circuit is being used toinduce sleep in the operator or to wake the operator up slowly. When theflip-flop 79 is set by the signal on line 67, the set state indicates awake up phase. Alternatively, when the flip-flop 79 is reset by a manualclosure of the switch 81, the sleep switch, the sleep inducing cycle ofthe vibrator will begin. Note that a diode 167 sets the flip-flop 69 inresponse to the switch 81 so that the flip-flop 69 is set for either thesleep or wake up mode. The output of the flip-flop 69 is connected tothe integrator 71, the output of which is at ground potential until theflip-flop 69 is set. At that time the output on line 73 changes linearlyfrom a high potential, the potential on line 103, to ground level, thepotential on line 105. The inverting amplifier output is opposite thatof the integrator 71, that is, when the flip-flop 69 is set, the outputon line 75 changes linearly from ground potential, the potential of line105, to a positive voltage potential, that of line 103. Each of theseoutputs on lines 73 and 75 are applied to the double pole, double throwsolid state switch 83, a commonly available integrated circuit.

When the flip-flop 79 is set by the alarm on line 67, and when theflip-flop 69 is set, a signal on line 169 will close a double pole,single throw solid state switch 171 to conduct the set voltages from theQ and Q outputs from the flip-flop 79 to the switch control inputs ofthe double pole, double throw integrated circuit switch 83.Alternatively, when the sleep switch 81 has been closed so that theflip-flop 79 is reset, but the flip-flop 69 is set, the signal on line169 will close the double pole, single throw solid state switch 171 toconnect the reset voltages from the Q and Q outputs of the flip-flop 79to the switch 83. The double pole, double throw integrated switch 83 iscontrolled by the outputs from switch 171 on lines 173 and 175, suchthat if the flip-flop 79 is set, indicating a wake up sequence, thenegative going ramp signal from the integrator 71 will be connected tooutput 177 of the switch 83, line 39, for controlling the astablemultivibrators. At the same time, the positive going ramp signal on line75 will be connected at output 179, line 60, of the switch 83 forcontrolling the monostable multivibrators. Alternatively, when theflip-flop 79 is reset indicating a sleep inducing phase, the output ofthe integrator 71 will be conducted by the switch 83 to the monostablemultivibrator on line 60, whereas the output of the inverting amplifier77 will be connected to the astable multivibrators on line 39. The stateof the flip-flop 79 in conjunction with the switch 83 thus conducts theoutput of the integrator 71 and inverting amplifier 77 to themultivibrators so that the astable multivibrator and the monostablemultivibrator in each half of the driving circuit receive a ramp signalgoing in opposite directions. During the wake up phase the vibratorsbegin at low frequency, low amplitude and cycle slowly to highfrequency, high amplitude. This operation is reversed when flip-flop 79is reset, that is, the vibrators begin at high frequency, high intensityand cycle slowly to low frequency, low intensity.

When the end of the cycle is reached, flip-flop 69 is reset by a signalproduced by the alarm reset and control circuit 86. Specifically, acomparator 85 produces an output voltage signal when the negative goingramp signal from the integrator 71 reaches the level of voltage on line105. The output 87 of this comparator 85 is ANDed with the Q output ofthe flip-flop 79 (indicating wake up rather than sleep phase) in an ANDgate 181, enabling a gate circuit 90 to energize an audio oscillator 94.A reset switch 92 resets the gate 90, when closed by the operator, todisable the audio oscillator 94. The oscillator is in turn connected tospeaker 96 to awaken the user. Also, upon resetting flip-flop 69, line169 opens the switch 171, which in turn opens the switch 83, therebyremoving all control voltages from lines 39 and 60. In addition, line169 disables a gate 182 (if switch 183 is open). The gate 182 thenproduces a signal on line 184 to disable all multivibrators 35,37,49,51.If the operator wishes to manually turn on the vibrator system withoutusing the alarm circuit, he closes switch 183, which enables the gate182 to produce a signal on line 184, enabling multivibrators 35,37,49,51 regardless of the state of the flip-flop 69.

From the foregoing description, it can be seen that the present circuit,in addition to permitting totally flexible control of both amplitude andfrequency of a pair of vibrators adapted for connection to a piece offurniture such as a waterbed, will slowly phase the amplitude andfrequency to produce a wake up and sleep mode. During the wake up mode,the amplitude and frequency start at low levels and are graduallyincreased to heighten the awareness of the individual before an audiblealarm sounds. During the sleep phase, the frequency and amplitude beginat a high level and are slowly reduced to induce a restful state in theuser.

What is claimed is:
 1. A vibrator system for inducing vibration infurniture, comprising:a pair of electrical-mechanical transducersmounted at spaced locations on said furniture, each of said transducersproducing output mechanical vibration, the amplitude and frequency ofwhich is independently controlled by the respective amplitude andfrequency of a pair of independent electrical driving signals; meansproducing said independent pair of electrical driving signals, saidmeans supplying independent cyclicly varying signals to each of saidpair of transducers, said means independently controlling the frequencyand amplitude of each of said pair of signals, said means comprising:apair of astable multivibrators; a pair of monostable multivibrators,each of said monostable multivibrators responsive to one of said astablemultivibrators and connected to drive one of said transducers; a pair ofswitching transistors, each of said transistors responsive to one ofsaid monostable multivibrators for controlling the current to one ofsaid transducers; and each of said pair of astable multivibrators andeach of said pair of monostable multivibrators including an independentcontrol element permitting control of the frequency and amplitude ofvibration of said transducers; and means producing an output ramp signalfor controlling said independent control elements of each of said twoastable multivibrators and each of said two monostable multivibrators.2. A vibrator for inducing vibration in furniture, comprising:meansresponsive to cylic driving electrical current for inducing mechanicalvibration in said furniture; and means producing said cylic drivingelectrical current, said driving current producing means comprises meansfor automatically changing said driving current with respect to timeover a predetermined period of time longer than the period of saidcurrent to alter said mechanical vibration over said period of time. 3.A vibrator for inducing vibration in furniture as defined in claim 2wherein said means producing said driving electrical current comprises:amultivibrator responsive to a time-varying control signal forcontinuously changing the time delay of said multivibrator; and meansfor producing said time-varying control signal.
 4. A vibrator forinducing vibration in furniture as defined in claim 3 wherein saidcontrol signal producing means comprises means for generating a linearramp signal.
 5. A vibrator for inducing vibration in furniture asdefined in claim 2 wherein said means producing said driving electricalcurrent comprises:an astable multivibrator automatically changing outputfrequency over said period of time; and a monostable multivibratorresponsive to the output signal of said astable multivibrator, saidmonostable multivibrator automatically changing its delay time over saidperiod of time.
 6. A vibrator for inducing vibration in furniture asdefined in claim 5 wherein said means producing said driving electricalcurrent additionally comprises:means producing a linear ramp signal forcontrolling each of said astable and monostable multivibrators.
 7. Avibrator for inducing vibration in furniture as defined in claim 2wherein said driving electrical current is cyclical and wherein saidperiod of time is long in comparison with the period of said cyclicalcurrent.
 8. A vibrator for inducing vibration in furniture as defined inclaim 2 wherein both the amplitude and frequency of said mechanicalvibration is automatically changed by said means producing said drivingelectrical current.
 9. A vibrator for inducing vibration in furniture asdefined in claim 2 wherein said means for producing said drivingelectrical current comprises means for modulating the amplitude of saiddriving electrical current.
 10. A vibrator for inducing vibration infurniture as defined in claim 9 wherein said means for modulating theamplitude of said driving electrical current comprises means forsuperimposing a time varying signal upon said driving electricalcurrent.
 11. A vibrator for inducing vibration in furniture as definedin claim 2 wherein said means for producing said driving electricalcurrent comprises means for modulating the frequency of said drivingelectrical current.
 12. A vibrator for inducing vibration in furniturecomprising:an electrical-mechanical transducer mounted on saidfurniture, said transducer producing output mechanical vibration theamplitude and frequency of which is controlled by an electrical drivingsignal; and means for producing said electrical driving signal, saiddriving signal producing means comprising means for automatically, andgradually altering said electrical driving signal with respect to timeover a predetermined period of time longer than the period of saidsignal to gradually change said mechanical vibration over said period oftime.
 13. A vibrator for inducing vibration in furniture as defined inclaim 12 wherein said means producing said electrical driving signalgradually increases the frequency and amplitude of said mechanicalvibration simultaneously.
 14. A vibrator for inducing vibration infurniture as defined in claim 12 wherein said means producing saidelectrical driving signal gradually decreases the frequency andamplitude of said mechanical vibration simultaneously.
 15. A vibratorfor inducing vibration in furniture as defined in claim 12 wherein saidmeans producing said electrical driving signal comprises:a firstmultivibrator the delay of which is responsive to an input controlsignal; and a ramp signal generator for producing said control signal.16. A vibrator for inducing vibration in furniture as defined in claim15 wherein said first multivibrator is astable and wherein said meansproducing said electrical driving signal additionally comprises:a secondmonostable multivibrator driven by said first multivibrator, said secondmonostable multivibrator having a time delay which changes in responseto said control signal.